A vast amount of energy is stored in the oceans and many ways have been proposed for utilizing this energy. Such methods include seawater batteries, floating wave generators, shore-based tidal dams and deepwater turbine platforms. Some also involve use of solar energy in combination with ocean thermal energy. Such ocean energy conversion systems are described by M. O. Zimmerman, Machine Design, Vol. 49, pp. 20-26, 1977, and C. Zener, Mechanical Engineering, Vol. 99, 26-29, 1977. A specific example of a power generation device utilizing the tropical water thermocline is described in U.S. Pat. No. 3,896,622 to G. T. Daniello. In this device a thermodynamic working fluid is vaporized by the warm surface water to raise a piston and the device is then lowered to the colder lower water where the working fluid is condensed and the falling piston does useful work. Another device utilizing a thermodynamic fluid is described in U.S. Pat. No. 3,984,985 to J. M. Lapeyre. This is a solar engine containing a relatively non-expandable fluid and a series of expandable and contractable chambers containing a thermodynamic fluid of lesser density than the non-expandable fluid. When the chambers are exposed to solar energy the thermodynamic fluid expands and forces the non-expandable fluid to the opposite side of the device where cooled chambers allow more non-expandable fluid to enter which causes a mechanical imbalance which in turn produces movement of the engine along a predetermined path.
In recent years studies of ocean thermal energy conversion have increased greatly and a large proportion of this effort has involved studies of heat exchangers, biofouling and corrosion. The heat exchanger component of an ocean thermal energy conversion power plant is the determining factor in achieving economic viability, since heat exchanger costs account for 40-60% of such a power plant costs.
It is an object of this invention to provide an efficient ocean thermal engine capable of utilizing the ocean thermocline.
Another object is to provide such an engine utilizing the hydrostatic pressure of the ocean.
A further object is to provide an ocean thermal engine in which the heat exchanger is combined with the engine.
A still further object is to provide an ocean thermal engine in which maintenance and cleaning costs associated with the fouling and corrosion of heat exchangers subjected to seawater are held to a minimum.